1. Technical Field
The present invention relates to an electrically electro-conductive belt, a fabrication method thereof, and an image forming device.
2. Related Art
Among electro-photographic image forming devices, a mode is common in which a toner image formed on a photoconductor surface is transferred to an intermediate transfer belt, and is transferred to a recording medium such as recording paper or the like at a secondary transfer portion.
For an electro-conductive belt such as the intermediate transfer belt in this mode of image forming device, it is desired that resistance values of an inner peripheral face and an outer peripheral face are controlled such that a resistance value of the inner peripheral face is small but a volume resistance is large, so as to prevent white spots, at which the toner transferred to the intermediate transfer belt detaches in the form of white spots, and suchlike.
As technologies for controlling to make the inner peripheral face resistance value of an electro-conductive belt small and the volume resistance large, there are, for example:
(1) An endless belt formed by centrifugal molding and including two layers: a front face layer formed of a thermosetting polyimide resin layer that is obtained by ring closure imidization of a polyimide precursor containing a conductive material; and a rear face layer formed of a thermosetting polyimide resin layer obtained by ring closure imidization of a polyimide precursor containing a conductive material. Both the front face layer and the rear face layer are obtained at the same time by ring closure imidization. The surface electrical resistance of the front face layer is 109 Ω/square to 1013 Ω/square and is larger than the surface electrical resistance of the rear face layer, and the volume electrical resistance of the endless belt has a value smaller than the surface electrical resistance of the front face layer;
(2) An endless tubular semi-conductive polyamideimide film belt in a condition in which, in a single layer, the electrical resistance of a rear face portion is smaller than that of a front face portion;
(3) A seamless belt with a base material consisting of a single layer that has different properties at a front face and a rear face due to an uneven distribution of an additive in the thickness direction;
(4) An electro-conductive belt at which the surface resistance of the inner peripheral face is lowered by a conductivity treatment being applied to the inner peripheral face side by spraying;
(5) A monolayer seamless belt formed of a polyimide resin containing a conductive filler of which conductive filler is uniformly distributed without bias in the thickness direction of the belt; and
(6) An intermediate transfer belt that contains plural kinds of carbon which are dispersed in substrates and whose conductivities are different, and among the plural kinds of carbon with different electrical conductivities, the carbon with the lowest conductivity is distributed to a front face side of the belt.